According to a journal article published earlier this month in Nature, the first genome sequence of an ancient bacterial pathogen has been completed. Yersinia pestis was extracted from the teeth of victims buried in a medieval cemetery. The results of the sequencing are really interesting.... Y. pestis, which caused the bubonic plague called the Black Death, hasn't really changed. There are only a few dozen changes among the more than 4 million DNA building blocks.

Before you get scared, you might want to refer to the title of this blog. The bacteria hasn't changed, but we have. Whew! Apocalypse averted, right?

The Black Death was deadly because of a combination of circumstances. In 1348, the climate was getting colder, the world was in the midst of a long war and horrible famine, and people were moving into closer quarters. All of these factors contributed to give the disease easy reach for infection and spread. In addition, people did not have any innate immune response; this was the first time the disease had attacked humans.

Today, simple antibiotics, such as tetracycline, can beat the bacteria. Interestingly, Y. pestis does not seem to have properties that enable other germs to become drug-resistant. Combine that with improved medical treatment, preparedness, and response by the health community, and we're set to avoid another plague-driven apocalypse...at least where the Black Death is concerned.

Other possibilities, both bacterial and viral, remain open for speculation by science fiction writers with vivid imaginations. Take the flu, for example....